It has long been known that achieving uniform circumferential turbine inlet temperature distribution in gas turbines is highly desirable. Uniform distribution minimizes hot spots and cold spots to maximize efficiency of operation. In addition, uniform distribution prolongs the life of those turbine components that are exposed to the hot gases.
To achieve uniform turbine inlet temperature distribution in gas turbines having annular combustors, heretofore one has had to provide a large number of fuel injectors to assure that the fuel is uniformly distributed in the combustion air about the annular combustor. Fuel injectors are quite expensive with the consequence that the use of a large number of them is not economically satisfactory. As the number of fuel injectors in a system is increased, with unchanged fuel consumption, the fuel flow area in each injector becomes smaller and thus, more prone to clogging.
This in turn creates the very problem, nonuniform temperature distribution sought to be done away with.
Furthermore, in relatively small turbine engines, wherein relatively low fuel flow rates may be encountered, it is highly desirable to minimize the number of the fuel injectors to minimize the possibility of clogging.
To avoid this difficulty, the prior art has suggested that fuel be injected into annular combustion chambers with some sort of a tangential component. The resulting swirl of fuel and combustion supporting gas provides a much more uniform mix of fuel with the air to provide a more uniform burn and thus achieves more circumferential uniformity in the turbine inlet temperature. However, this solution deals only with minimizing the presence of hot and/or cold spots and does not focus on the remaining problem where gases of combustion may impinge upon components in a uniform manner but at excessive temperatures.
The present invention is directed to overcoming one or more of the above problems.